Toronto Photography Meetup Group

Hi

I'm using a Canon 50d with a Contax Planar 50mm F1.7 lens which has been adapted and has an auto focus confirmation chip.

My question is what metering mode should I be using to get the right exposure?

The reason I'm asking is I remember reading a recommendation that spot metering should be used with manual lens. Something about the characteristics of the lens not being available which could cause the photo to be under or over exposed. Usually I use center weighted metering mode.

I don't think you can go wrong with spot or centre-weighted TTL metering.

You may be thinking of Nikon matrix metering which takes into account focus distance which the manual lens does not provide.

I'm not familiar with Canon metering to know about their particular caveats.

Hi Ofmod

To be more clear about my confusion, I usually use "partial metering". The problem appears that for some reason I seem to often get over exposed shots when I use this manual lens. This is not a problem with my 17-40 or 70-200. My general guess is because the SLR can identify the lens and may know how to fine adjust exposure based on the lens characteristics. As a test I did notice spot metering seem to be more accurate for this lens.

So my follow up question is then based on this being a manual focus lens on a canon what metering modes are compatible?

is the aperture automatically set? If not that might be the problem.
The camera meter assumes the aperture is wide open when it does the metering. Having a small aperture might confuse the meter.

I am not an alt lens user but a buddy of mine shoots a Canon 5D with all manual glass that does not communicate with the camera. If I recall, the exif data will state F0 for aperture. He routinely meters with the lens stopped down to the aperture he intends to use and it works fine.

Perhaps someone like Mawz can chime in on this topic as he has extensive experience in this area.

Hi Guys

Thanks for the input. When I shoot it is usually between F1.7 and F5.6. In my case I manually adjust the aperture via the ring.


My current steps when shooting in M (manual):

*Meter is set at partial metering


(1) Set physical lens f-stop to F1.7

(2) Set in camera f-stop to desired f-stop (e.g F2.8 )

(3) Focus lens till I get confirmation beep from camera

(4) Press shutter button half way and adjust exposure time to center light meter.

(5) Set physical lens f-stop to intended setting (e.g. 2.8 )

(6) Press shutter button completely down to take picture.

I've been using manual focus lenses for a long time now. Overexposure is a common variable that you have to take into account. The more you stop the lens down, typically the more overexposure, that is why you use the exposure compensation function on your camera. Each lens has its own characteristics and you have to determine the level of exposure compensation based on the specific lens and the aperture you are using.

Hi Sandeep

So are you saying you can use any metering mode on a manual lens?

most lenses require centre-weighted mode, I've never had any issues with my Takumar, however, I wouldn't generally rely on centering the needle in the meter, you do have to think what your subject has in terms of light intensity as camera's meter is usually set to 18% grey, which in a lot of cases doesn't produce 100% accurate exposure, shoot raw and compensate. I would focus first then stop down the lens and meter

I've tried center-weight before without much of a noticible change. I prefer to leave it on evaluative mode most of the time. I just dial in the appropriate exposure compensation level based on the aperture I'm going to use, shoot and have a quick look at the image histogram after the shot to make sure I'm not loosing image details or need to adjust my exposure compensation.

Just try and experiment. So with your Planar at f1.7 to f2.8, you may not need any exposure comp, at f4 you might need to dial in -0.5 and at f5.6 you might need to dial in -1 to -1.5. I typically shoot in AV mode, that and Manual are the only two modes available to you.

Incidently focus confirm adapters are not that accurate as precise manual focusing. I prefer adapters without the chip and use Live View with 5x or 10x magnification for precisely focus on my subject. I've found this to be the most precise and now use it all the time over having used other focus aids in the past - AF confirm adapters, Canon Angle Finder C and Katz Eye microprism focusing screen.

The over exposure issue when stopped down is more pronounced with consumer bodies. I don't have any issues with 1Ds, 1D II bodies. Metering is well within tolerance with them.

Thanks for the input guys. Based on the responses it sounds like any metering mode should work. The key to metering accurately seems to choose the best mode for the situation (which is what I have been experimenting with).

That being said .... any one have recommendations on an article or book which discusses the zone system for light metering? I've been reading the below article but I'm looking for other examples so I can get the thought process clear in my head.


http://www.forphotography.com/how-tos/zone/zone1.html

step (4) & (5), shouldn't you adjust the physical aperture to the desire setting first, before taking an exposure reading? i.e., 4&5 reversed

Hi Fchang



When your not using an AF confirmation adapter I would definitely set the physical aperture after focusing.

In my case the AF confirmation adapter from BIG_IS allows me to record the actual aperture I am taking the picture at. So when I stop down in camera (not on lens) the light meter automatically compensates the readings. So my steps would be applicable to using this type of AF confirmation adapter. Note that the lens is wide open while I take the exposure readings.

Thanks for the info. I didn't know that AF confirmation adapter will also relay aperture info for exposure reading.

Your welcome. It was a surprise for me as well.